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Decagon
From Wikipedia, the free encyclopedia
In geometry, a decagon is any polygon with ten sides and ten angles, and usually refers to a regular decagon, having all sides of equal length and all angles equal to 144°, therefore making each angle of a regular decagon be 144°. Its Schläfli symbol is {10}. The area of a regular decagon of side length a is given by
A regular decagon is constructible with a compass and straightedge.
- Complete steps 1 though 6 of constructing a pentagon.
- Extend a line from each corner of the pentagon through the center of the circle made in step 1 of constructing a pentagon to the opposite side of that same circle.
- The five corners of the pentagon constitute every other corner of the decagon. The remaining five corners of the decagon are those points where the lines of step 2 cross the original circle (but not a pentagon corner).
- Eric W. Weisstein, Decagon at MathWorld.
- Definition and properties of a decagon With interactive animation
| Polygons |
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| Triangle • Quadrilateral • Pentagon •Hexagon • Heptagon • Octagon • Enneagon (Nonagon) • Decagon • Hendecagon • Dodecagon • Triskaidecagon • Pentadecagon • Hexadecagon • Heptadecagon • Enneadecagon • Icosagon • Chiliagon • Myriagon |
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